{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/117720"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/117720","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Probing hidden sectors with early universe cosmology","abstract":"Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2023-04-12 without embargo terms","abstract_html":"Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2023-04-12 without embargo terms","abstract_has_math":false,"creators":["Ralegankar, Pranjal"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Shelton, Jessie","Adshead, Peter","Holder, Gilbert","Kahn, Yonatan"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2022,"date_issued":"2022-12","date_published":"2022-12","updated_at":"2026-07-22T22:24:56Z","subjects":["Cosmology","Dark Matter","Dark Radiation","Early Universe"],"languages":["en","eng"],"rights":["Copyright 2022 Pranjal Ralegankar"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/117720","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Shelton, Jessie","Adshead, Peter","Holder, Gilbert","Kahn, Yonatan"]},{"key":"dc:creator","label":"Author","values":["Ralegankar, Pranjal"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2022-12","2022-09-16"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Physics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Cosmology","Dark Matter","Dark Radiation","Early Universe"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en","eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2022 Pranjal Ralegankar"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/117720"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2023-04-12 without embargo terms","The student, Pranjal Ralegankar, accepted the attached license on 2022-09-12 at 13:26.","The student, Pranjal Ralegankar, submitted this Dissertation for approval on 2022-09-12 at 13:38.","This Dissertation was approved for publication on 2022-09-16 at 11:51.","DSpace SAF Submission Ingestion Package generated from Vireo submission #18486 on 2023-04-12 at 07:23:28","There is no fundamental requirement for all particles to be charged under the Standard Model gauge symmetries. Consequently, there could naturally be a hidden sector of particles that have gone undetected and dark matter could reside in it. A hidden sector of particles could naturally have a different temperature than the plasma formed by the Standard Model particles in the early universe. Such a hidden sector can alter early universe cosmology from the assumed behavior in a variety of ways, which we explore in this thesis. First, we discuss how both hidden sector and Standard Model sector can be populated via inflaton decays after inflation. Next, we explore how thermally decoupled hidden sector with a massive lightest particle (m ≫ MeV) can enhance the abundance of sub-Earth mass dark matter microhalos today. We then explore how hidden sectors with a massless lightest particle can cause an inhomogeneous distribution of helium to hydrogen ratios if the hidden sector never had any interaction with the Standard Model sector. If instead the hidden sector had some interaction, then we show how the constraints on dark radiation energy density can be employed to constrain the interaction strength between the two sectors."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Probing hidden sectors with early universe cosmology"]}]}],"canonical_facts":{"dc:contributor":["Shelton, Jessie","Adshead, Peter","Holder, Gilbert","Kahn, Yonatan"],"dc:creator":["Ralegankar, Pranjal"],"dc:date":["2022-12","2022-09-16"],"dc:description":["Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2023-04-12 without embargo terms","The student, Pranjal Ralegankar, accepted the attached license on 2022-09-12 at 13:26.","The student, Pranjal Ralegankar, submitted this Dissertation for approval on 2022-09-12 at 13:38.","This Dissertation was approved for publication on 2022-09-16 at 11:51.","DSpace SAF Submission Ingestion Package generated from Vireo submission #18486 on 2023-04-12 at 07:23:28","There is no fundamental requirement for all particles to be charged under the Standard Model gauge symmetries. Consequently, there could naturally be a hidden sector of particles that have gone undetected and dark matter could reside in it. A hidden sector of particles could naturally have a different temperature than the plasma formed by the Standard Model particles in the early universe. Such a hidden sector can alter early universe cosmology from the assumed behavior in a variety of ways, which we explore in this thesis. First, we discuss how both hidden sector and Standard Model sector can be populated via inflaton decays after inflation. Next, we explore how thermally decoupled hidden sector with a massive lightest particle (m ≫ MeV) can enhance the abundance of sub-Earth mass dark matter microhalos today. We then explore how hidden sectors with a massless lightest particle can cause an inhomogeneous distribution of helium to hydrogen ratios if the hidden sector never had any interaction with the Standard Model sector. If instead the hidden sector had some interaction, then we show how the constraints on dark radiation energy density can be employed to constrain the interaction strength between the two sectors."],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/117720"],"dc:language":["en","eng"],"dc:rights":["Copyright 2022 Pranjal Ralegankar"],"dc:subject":["Cosmology","Dark Matter","Dark Radiation","Early Universe"],"dc:title":["Probing hidden sectors with early universe cosmology"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Physics"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:56Z"}